For digital color images, the image quality depends on whether the color images are colorfully vivid. The color saturation is an important parameter on determining the vividness of the color images. Therefore, adjusting the color saturation has become a key technique as to improve the image quality of digital color images.
A conventional method to adjust the color saturation for color pixels composed of R, G, B signals, for example, is to convert the R, G, B signals into Y (for luminance) and C (for color (or hue)) signals at first and then adjust the C signals. More particularly, C signals can also be known as different terms for different systems. For example, C signals can be IQ signals for NTSC (National Television Standards Committee) and UV signals for PAL (Phase Alternate Line). Moreover, C signals can be further divided into Cb and Cr signals.
Even though, in the prior art method, C signals are adjusted by adjusting Cb and Cr signals, this simple approach leads to other problems such as Cb and Cr being adjusted simultaneously. As a result, the color saturation for digital color images is re-adjusted while Cb and Cr are adjusted. Therefore, when the color saturation for one color of the digital color image is adjusted, the color saturations for other colors will be affected, thus degrading the image quality.
Accordingly, color aberration occurs in digital color images due to Cb and Cr being adjusted in the prior art method for color saturation adjustment.
In addition to color aberration, low color contrast occurs when the color saturations for all colors are adjusted simultaneously.
Therefore, there is need in providing a method and a device for independent color management making it feasible to adjust the color saturation of a single color independently so as to improve the image quality of digital color images.